The largest public works project in state history has turned into a huge cash cow for Honolulu Mayor Kirk Caldwell's campaign.

A Hawaii News Now analysis found that Caldwell received more than $916,000 during the past two elections cycles from rail contractors, subcontractors and their executives.

Those same companies and their employees contributed more than $346,000 to all nine City Council members.

"This really doesn't look good. It's legal but it doesn't mean it's ethical," said Colin Moore, a University of Hawaii Political Science professor.

"People are already confused about why the rail system is costing so much. They see the contractors are being compensated generously."

Caldwell campaign officials said the contractors support the mayor because he's committed to the project.

And they stressed that the mayor has no say in awards of the rail contracts. That's done by the rail authority, the Honolulu Authority for Rapid Transportation or HART, which is an independent city agency.

"For someone who believes in rail and believes it will make a positive impact on our community, I would certainly think they would support the mayor," said Lex Smith, chair of Caldwell's campaign.

By contrast, Charles Djou, Caldwell's opponent in the November general election, received $34,000 from those same rail interests.

"Unlike the mayor I'm not willing and haven't taken hundreds of thousands of dollars and lined my campaign coffers with money from rail contractors," Djou said.

"The fact that the mayor has taken so much money from so many rail interests here, it damages his objectivity and ability to be independent."

Hawaii News Now's analysis was based on thousand of contributions from more than 300 contractors, subcontractors, executives and their relatives.